Freddy Patel, the pathologist who conducted the first postmortem on Ian Tomlinson, has been found guilty by a medical tribunal of misconduct, deficient professional performance and dishonesty.

An independent fitness to practice panel said Patel had brought his profession into disrepute and had shown "a closed mindset" in April 2009 when he had attributed Tomlinson's death during the G20 protests to coronary heart disease.

Patel did not change his mind after he had seen video footage of Tomlinson being struck to the ground, despite finding fluid and blood in Tomlinson's abdominal cavity, or when three other pathologists considered Tomlinson had died as a result of bleeding from a traumatic liver injury caused by a push and fall to the ground.

He also lied about his status, allowing him to remain on the official Home Office register of forensic pathologists on which he was still listed when the City of London coroner Paul Matthews summoned him to establish Tomlinson's cause of death.

The panel found he had deliberately concealed that he was not on a group practice of pathologists, a requirement to remain on the register after 2006, as it also reviewed Patel's failures in other cases dating back to 2002. Patel had been suspended from the medical register – the database of doctors legally allowed to practise in the UK – for other failures in 2010 and 2011.

Panel chair Robert Lloyd-Richards said: "It is clearly in the interest of the general public that they should be able to have confidence in the coronial system and this confidence has been undermined by your failures in these cases.

"Having considered everything before it the panel has determined that your fitness to practise … is impaired by reason of misconduct and deficient professional performance in the case of Mr Tomlinson."

The independent panel sitting for the Medical Practitioners Tribunal Service, part of the doctors' professional regulator, the General Medical Council, will now decide what professional sanctions Patel should face. Government agencies have made it clear it is impossible to know whether Patel would have been called to examine Tomlinson's body if the facts about his CV were known at the time.

Coroners have the jurisdiction on choosing who does postmortems and there is no legal requirement for them to use a forensic pathologist on the register.

The National Police Improvement Agency, which administers the list, says it has implemented a series of measures to ensure that forensic pathologists perform to the highest standards.

In September 2010 Paul Matthews, the City of London coroner, issued a statement saying that when he had appointed Patel to conduct Tomlinson's postmortem, the pathologist was a fully registered medical practitioner (the only qualification required by the Coroners Act) and was also on the Home Office register. Attempts by the Guardian to contact him on Tuesday were unsuccessful.

Meanwhile, Simon Harwood, the police officer who pushed Tomlinson to the ground, will face disciplinary proceedings on 17 September. Harwood was acquitted of manslaughter in connection with Tomlinson's death in July, but the Independent Police Complaints Commission has ordered that he face an internal Metropolitan police hearing in public. Scotland Yard said there would be a gross misconduct hearing in front of a panel of three people, including a senior officer and a lay person. It is expected to last up to four weeks.

Harwood hit Tomlinson with his baton and shoved him to the ground near the Royal Exchange buildings in London. The 47-year-old, who was an alcoholic and had slept rough for a number of years, managed to walk 75 yards before he collapsed and later died from internal bleeding.

Harwood told jurors at Southwark crown court he had used only reasonable force, and was cleared of killing the father-of-nine. Jurors in an inquest into the death had earlier returned a verdict of unlawful killing.

Julia Tomlinson, Tomlinson's widow, said "The incompetence and dishonesty of Freddy Patel helped PC Harwood and gave us an uphill battle for justice from the start. He misled everyone saying that Ian had died of a heart attack when in fact he had died of internal bleeding. It's good that people can see some of the things we have been up against.

"Patel has a lot to answer for and I would like to know why with all the good pathologists there are he was selected to do the first postmortem."

Patel has faced a number of disciplinary hearings. In 2002 he was reprimanded for breaching patient confidentiality in 1999 by telling journalists that Roger Sylvester, a 30-year-old who died in police custody, had been taking crack cocaine.

In October 2010 Patel was suspended from the medical register after a disciplinary panel concluded he was "irresponsible" and failed to meet professional standards during his examinations of the bodies of a five-year-old girl in 2002, a four-week-old baby in 2003 and a woman who died in 2005.

In March last year he was found to have falsified his CV and to have conducted a botched autopsy in 2002 on the body of 31-year-old sex worker Sally White, who was the first victim of 'Camden Ripper' Anthony Hardy.

Patel suggested White had died from a heart attack during consensual sex despite evidence of blood-stained clothing and bedding. This discouraged a police investigation that might have saved two later victims of Hardy.

The Metropolitan police's contract with Patel was not renewed in 2004.

• This article was amended on 22 August 2012. The original said GMC panel instead of tribunal. This has been corrected.